-^^T ■^^"^ S^<<^"^^ cute::" circinensis. lateral line of 33-40 scales (7. angulatus. from dorsal to lateral line 5 scales ; base of anal extending beneath that of dorsal ; form sh(H't and deep . G. guntheri. base of anal behind that of dorsal ; form elongate .... (7. alius. ON THE SPECIES OF THE GENUS CHALCINUS. 6 Scales from upper edge of gill-opening to caudal 40-47 ; rays in the anal fin 27-32 ; first anal ray behind the dorsal . O. elongatus. rays in the anal 30-34 ; first anal ray beneath middle of dorsal G. culler, rays in the anal 35-41 ; first anal ray in front of dorsal (7. jnagdalenm CHALCINUS ANGULATUS Spix and Ag. ; C. V. G. brachipoynus C. V. G. mulleri Fil. C. Irifurcalus Cast. G. nemalwus Kn. Triportheus -fiavus Cope. Valenciennes states in his description of G. brachipomus that the length is about three and a half times the height and nearly five times the length of the head, which propor- tions, together with the characters assigned it, seem tone- cessitate placing it as asynonyme with G. angulatus. G. brachypomus of Glinther is so different in essential respects from that of Valenciennes that the two cannot be considered identical. On typical specuiiens of G. angulatus the labial folds and the barbels are short, apparently ; in this and in the other species, they are longer in the young than in the old, and it may be they are the more developed in the spawning season. One of the varieties has a length of barbel that equals or exceeds the diameter of the eye. Examina- tion of a large number of specimens discloses no variation in the number of scales (6) between the first ray of the dorsal and the lateral line. Hab. Coary, Cudajas, Fonteboa, Hyavary, Iga, Jutahy, Lake Hyanuary, Lake Jose Assu, Manacapouru, Manaos, Obydos, Santarem, Silva, Lake Sa- raca, Tabatinga, Telfe, Tonantins. The species as represented in the collection is separable into four varieties beside the type form. 4 ON THE SPECIES OF THE GENUS CHALCINUS. 1. G.curtus.. Distinguished by the shortness of its body and the roundness of its outlines, its depth being more than one-third of its length, without the caudal. The lo- calities indicated are Para and Arary. 2. C. vittatus. Marked by the possession of two or more longitudinal bands on the flank, formed by a spot of dark color about the middle of the posterior border of each scale in the row. Commonly there is a patch of brown near the base of the pectoral. Taken at Jose Fernandez, Villa Bella, Porto do Moz, and Santarem. 3. G. signatus. The bands are absent from the flanks of this form ; it is darker on the upper surface than the pre- ceding; the fins are darker on their edges, and there is a transverse band of light color on the caudal. The flanks are silvery. Hab. Rio Puty. 4. C.fuscus. On this form the back is very dark ; the sides have a golden reflectionbut the scales are broadly mar- gined with brown on their free edges which makes the fish appear dark colored. Top of head, lips and barbels nearly or quite black. Fins, brownish. Barbels, as long as the eye. From Villa Bella and Lake Hyauuary. CHALCINUS PARANENSIS Gthr. D. 11, A. 30, L. 1. 32. According to the description this species has thirty rays in the anal fin, thirty -two or thirty-three scales in the lateral line, six scales between the latter and the first ray of the dorsal, and the length without the caudal is equal to two and two-thirds times the height or four times the length of the head. Described from the Parana river. CHALCINUS GtJNTHERI UOm sp. n. C hracliyi^omus Gthr. D. 11, A. 28, V. 7, L. 1. 34. In this species there are but five scales in a series between ON THE SPECIES OF THE GENUS CHALCINUS. 5 the first ray of the dorsal and the lateral line, and between the Litter and the ventral but a single one. Taking one from the San Francisco river as a typical specimen, it is found to have thirty-two rays in the anal, thirty-one scales in the lateral line, counting those on the tail with the others, and its length is about two and one-half times its height or nearly three and three-fourths times the length of the head. CHALCINUS PICTUS sp. n. D. 11, A. 24 (23), V. 7, L. 1. 32, L. tr. ^^. This species may be classed with the angulata group. Though not quite as slender as the next in order, it bears some resemblance in shape. A specimen from Jutahy, of five and one-eighth inches, has a length of three times the height or four times the length of the head. There are five scales between the first ray of the. dorsal and the lateral line, one between the lat- ter and the ventral, and two between the lateral line and the lower edge of the body. Barbels small ; labial folds well marked ; intermaxillary teeth in two slightly irregular series. Eye moderate ; its diameter is more than one-third of the length of the head and nearly twice the length of the snout. Head rather broad, not very convex between the orbits, which latter are little narrower than the inter- orbital space. The base of the anal begins a little distance behind the end of that of the dorsal. Color, in alcohol, golden, lateral edges of scales brown- ish, top of head light, back little darker. A triangular patch of brown is seen on the pectoral fin, near the base ; behind this there is a band of light color, parallel with the posterior border, which is narrowly edged with dark. The middle rays of the caudal are dark ; on each side of this dark band there is a light area in front of a transverse black band on the extremity of the fin. 6 ON THE SPECIES OF THE GENUS CHALCINUS. Chalcinus ALBUS. Triportheus albus Cope, juv. Chalcinus Knerii St., adult. D. 11, A. 29-32, L.l. 30-33. Five scales between the first ray of the dorsal and the lateral line were present on all the specimens examined. The anal fin begins at a little distance behind the base of the dorsal. The middle rays of the caudal are not black as in the preceding ; the extremity of the fin is crossed by a black band, in front of which there is a white one. Secured at Manacapouru, Porto do Moz, Tabatinga, Ta- japura, Tefie, Rio Negro, Hyavary and Iga. Chalcinus elongatus Gth. "D. 11, A. 28, V. 8, L. 1. 45, L. tr. -f--" A considerable variation is to be seen in regard to the amount of convexity of the crown ; on the young or on the lean it is much less than on the more plump of the older ones. The barbels are more prominent on the young. The anal rays vary in number from 28 to 32, the scales in the lateral line from 43 to 48, and the scales between dor- sal and lateral line from 6 to 7. Next to C. angulatus, this species is probably the most common. It was taken at Arary, Cameta, Gurupa, Tga, Jose Fernandez, Jutahy, Lago Alexo, Lake Hyanuary, Lake Jose Assu, Manaca- pouru, Manaos, Montalegre, Obydos, Para, Porto do Moz, Rio Negro, Santarem, Silva, Lake Saraca, Tabatinga, Tetfe, Tonantins and Villa Bella. Chalcinus magdalen^e St. "D. 11, A. 35-41, V. 7, L. 1. 41." Six and a half to seven rows of scales above the lateral line, and one and a half rows below it to the ventral, or ON THE SPECIES OF THE GENUS CHALCINUS. 7 three to the lower edge of the body. In this species the base of the anal extends forward to or beyond a vertical from the front extremity of that of the dorsal. Hab. Mag- dalena, Cauca, Guayaquil. Chalcinus culter Cope. D. 11, A. 31-36, V. 7, L. 1. 44-48. There are seven scales above the lateral line to the me- dian line on the back. Localities, I§a, Sao Paolo, Teffe. ON SPECIES OF GASTEROPELECUS. BY S. GARMAN. Gasteropelecus sternicla L. ; Pall. From a Surinam specimen the formula is D. 11, A. 34, L. 1. 33, pores 17, D. to A. 14. Numerous specimens from Tabatinga, Lago Alexo and Para, adult and young, agree closely with this. In the lateral line there is a variation of about three scales, 31-33. Very young ones have mi- nute dots of black pigment in a band on each iBank nearly or quite to the head, and in another along the entire lower edge at the base of the anal ; they are also more or less thickly sprinkled along the back, over the body and under the chin. Large specimens show similar markings, but, being darker, their marks are less distinct. Specimens from Curupira and Cudajas indicate a wider range of va- riation : D. 11-12, A. 33-37, L. 1. 30-35. Gasteropelecus stellatus Kn. D. 14-16, A. 39-42, L. 1. 20-22. A large scries of specimens were preserved at each of the following localities : Coary, Hyavary, Manacapouru, Montalegre, Obidos, Sao Paolo, Tabatinga, Teffe and Villa Bella. An individual from Paraguay has D. 15, A. 42, L. 1. 21, which docs not distinguish it from those of the Amazon. A common mark of the species may be seen in (8) ON SPECIES OF GASTEROPELECUS. 9 a brown spot on the anterior rays of the dorsal, and another in the brownish color of the interior or central rays of the pectoral. Gasteropelecus pectorosus sp. n. D. 15-16, A. 36-40, L. 1. 21 (19-22). The specimens to which this name is given are readily separated from the preceding by the difference in shape. In those of equal length, when compared with G. stella- tus, G. pectorosus is found to be one-fifth deeper from back of head to lower edge of sternal expansion, the an- terior edge of the latter approaching the vertical and be- ing more nearly straight. Or, if specimens of equal depth are compared, G. stellatus is seen to be one-third the longer. As far as may be determined from the descrip- tion of G. securis, of Filippi, its shape approaches that of G. pectorosus; the former is possessed of a larger num- ber of rays (44) in the anal fin. In the Litter the pecto- rals reach farther back than the base of the dorsal. Meas- urements from those taken at Manacaponru make the length of one, to base of caudal, two and one-fourth, and the depth one and seven-eighths inches. Of another, the length is one and seven-eighths inches and the depth one and one- fifth. Secured at Cudajas, Lago Alexo, Obidos, Taba- tinga and Manacapouru. Gasteropelecus fasciatus sp. n. G. strigatus St. D. 10, A. 25-27, L.l. 30-32. The outline of this fish is similar to that of G. sternicla but it is readily distinguished by its markings. Along the anal margin at the base of the fin there is a narrow band of dark color ; parallel to this and half way to the base of the pectoral there is a broader band of similar color ; ESSEX INST. BULLETIN, VOL. XXII 1* 10 ON SPECIES OF GASTEROPELECUS. a third band parallel with the other two passes through the base of the pectoral from the breast to the lateral line ; and a narrow stripe of light color edged with darker, ex- tends along the vertebral column on each flank. Usually there are several indistinct spots of darker color on the back, above the light stripe, one of Avhich is situated at the hinder end of the base of the dorsal. A couple of short streaks of dark from the chin appear to meet in an acute angle just behind the eye. The thoracic bands are separated from each other by bands of light color equally wide. In coloration this form resembles to some extent G. stngaius of Giinther which is said to have four blackish bands on the thorax, radiating from the middle of its con- vex edge, in addition to a blackish band along the base of the anal fin, and the formula is D. 9, A. 27, L.l. 25. A large number of specimens have been examined, but without discovering one on which there were less than thirty scales in the lateral line. Specimens from Lake Saraca have faint markings, those from Cudajas have them more distinct, but yet appearing faded, while the darkest and most vivid are on those from Manacapouru and Tabatino^a. ON SPECIES OF CYNOPOTAMUS. BY S. GARMAN. Cynopotamus gibbosus L. ; C. V. Search for variation in the luiinber of dorsal rays proved without avail, the number eleven is very constant. The range of variation in the anal includes about ten rays, 50-60. The scales in the lateral line vary from 57-62 ; in the transverse series between the first ray of the dorsal and that of the anal there are usually sixteen scales above the line and fourteen below, rarely fifteen above and thir- teen below. The humeral and the caudal spots also vary greatly, being more often present on the young ; sometimes they are absent entirely on specimens from localities whence the greater number are well marked. Collected at Coary, Cudajas, lea, Javary, Jutahy, Lake Hyanuary, Manacapouru, Manaos, Obydos, Porto do Moz, Rio Negro, Serpa, Silva, Lake Saraca, Surinam, Tabatinga, Uerandu- ba and Villa Bella. Cynopotamus pauciradiatus. Anacyrtus pauciradiatus Gth. A considerable number were received from Lago do Maximo and Villa Bella. On those of a couple of inches in length, the spots on shoulders and tail are distinct. The rays in the anal vary from 44 to 46 ; the scales in the lateral line from 55 to 57 ; and in the transverse line be- (11) 12 ON SPECIES OF CYNOPOTAMUS. tvveen the anterior rays of dorsal and anal there are com- monly 12 scales above the line and 12 below ; an occasional specimen reaches 13. Cynopotamus molossus Kner. On such as were examined the formula stood as follows : D. 11, A. 43-47, L.l. 46, L.tr. -^- Humeral and caudal spots distinct on the numerous small specimens from Serpa and Jutahy. Cynopotamus microlepis. E]Jicyrtus microlepis Rht. On specimens from Obydos there are fifty- seven rays in the anal, ninety-seven scales in the lateral line, and in the transverse series there are twenty-four above the line and twenty-three below it. Cynopotamus affinis. Anacyrtus affinis Gth. Anal rays varying from 53 to 57, scales in the lateral line from 73 to 80, and in the transverse series between dorsal and anal there are 20 to 22 scales above the line and 17 to 19 below it. Humeral and caudal spots small to absent. Collected at Iga, Coary, Javary, Jose Fer- nandez, Jutahy, Lago Alexo, Lake Hyanuary, Lake Sar- aca, Manacapurua, Sao Paolo and Serpa. Cynopotamus myersii. liceboides myersii Gill. D. 11, A. 51-56, L.l. 88-95, L.tr. Igf- From the number of specimens collected and the locali- ties this would appear to be one of the most widely dis- tributed and plentiful of these fishes. Hab. Coarj^ Fon- tcl)oa, Javary, Jutahy, Jose Fernandez, Lago Alexo, ON SPECIES OF CTNOPOTAMUS. 13 Lake Hj'anuaiy, Manacapoura, Kio Puty, Sao Paolo, San Gongallo, Serpa, Tabatinga and Tonantius. Cynopotomus xenodon Rht. ; Ltk. D. 11, A. 50, L.l. 66, L.tr. 4^• In shape and markings the specimens placed under this name closely resemble G. pauciradiaius. The rays in the anal vary from 48 to 55, the scales in the lateral line from 61 to 70, and those in the transverse series from 14 to 16 above the line and from 13 to 14 below it. Large num- bers were taken at Lake Saraca and at Serpa ; it was also secured at Arary, Lago Alexo and Obydos. Cynopotamus guatemalensis. Aiiacyrtns guatemalensis Gth. On a couple of a number of individuals from the Chagres river, the formula is D. 11, A. 48-50, L.l. 83-90, L.tr. ^^' The depth of the body is about two and three- fourths times and length of the head four and one-third times in the total length, without caudal. Cynopotamus knerii. Anacyrtus knerii St. D. 11, A. 46, L.l. 86, L.tr. -g- Small specimens from Tabatinga have a distinct caudal blotch but are without the humeral spot. The silvery band on the flank is narrow but well defined. Cynopotamus humeralis C. V. Near the middle of its length the silvery band of the flank occupies the six scales immediately above the lateral line. The humeral and the caudal spots vary much in depth of color, usually both are present. The number of 14 ON SPECIES OF CYNOPOTAMUS. rays in the anal vary from 42 to 46. Huh. Rosario, Goyaz, and Sao Paolo. Cynopotamus biserialis sp.n. D. 11, A. 47, V. 8, P. 13, L.l. 62, L.tr. 4^' Both upper and lower jaws without external toothlike processes; no canines; teeth conical, in two series on in- termaxillaries and on the anterior halves of the mandibles ; a single series of maxillary teeth. The two series of teeth on the mandibles serve as a ready means of distinguishing this species from G. gibbosus, and 0. pauciradiatus, which it approaches in shape. The back is elevated, decurved toward the occiput, and the depth is one-third of the leno;th to the bottom of the caudal notch. The head is a little more than one-fourth of the length, excluding the caudal. Eye large, two and two-thirds times in length of head, wider than interorbital space. The maxillary near- ly or quite reaches a vertical through the centre of the eye. The fourth or fifth ray of the dorsal fin is in the middle of the entire length, without the caudal, and the anterior ray of the dorsal is slightly behind that of the anal. Flanks silvery, humeral and caudal spots present. Many examples were secured by the Thayer Expedition at Lago do Maximo, Obydos and Villa Bella. ON THE SPECIES OF THE GENUS ANOSTOMUS. BY S. GARMAN. The characteristics of the various fishes credited to it are such as to divide the genus Anostomus into three com- paratively distinct groups or subgenera. The large series collected by the Thayer Expedition for the Museum of Comparative Zoology illustrate this to advantage, and at the same time they furnish several types that do not ap- pear to have previously been noticed by ichthyologists. The first of the groups {Anostomus) is characterized by an elongate narrow snout, of which a cross section in front of the eyes would be nearly round, by a mouth turned almost directly upward and by long, .slender, crenulate mandibular teeth. It contains but two of the species. The second group, to which the name Sclnzodontojjsis is given, is marked by a short broad snout, of which a trans- verse section behind the nostrils would be sub-elliptical ; by a mouth turned obliquely upward and forward, and by teeth on the mandible that are broad and truncate, having entire or chisel-shaped edges. Four species of close affin- ities are to be included in this group. The third of the sub-genera (Schizodon) is similar to the second in shape of snout, but the mouth is directed forward or, in one species, obliquely downward, and the mandil)ular teeth are short, broad, and crenulated. This section includes the six re- maining species. The characters assigned Scliizodon sag- (15) 16 ON THE SPECIES OF THE GENUS ANOSTOMUS. ittaiHus will not permit its admission. Apparently it is the young of Rhytiodon argenteo-fuscus. The fourth tooth on each side in that species is very small and from its position against the third is not readily discovered. The teeth of the species of Rhytiodon differ considerably, and Kner's figures of those of R. microlepis do not Avell represent those of R. argenteo-fuscus, which latter agree somewhat well with those of 8. Sagittarius as described. Aside from the six teeth on the mandible there is nothing in the description that will separate Sagittarius and argenteo-fuscus. The differences between Rhytiodus and Anostomus seem too irreat to allow of brin: them tooether as subojenera. In the following table are indicated the different divis- ions of the genus Anostomus with their contents. Snout elongate, narrow, sub-circular in cross section ; mouth directed upward, lower teeth long, narrow, crenulate . . (Anostomus). series of scales 4 from L.l. to D. ; flank with two longitudinal bands sahnoneus. series of scales 6 from L.l. to D. ; flank with two or more spots . irimaculatus. Snout broad, sub-elliptic in cross section ; mouth directed obliquely upward and forward, lower jaw longer ; lower teeth broad, truncate or chisel-shaped (ScHIZODONTOrSIs) . series of scales 5 from L.l. to D. ; a band along the flank . . . tceniatus. series of scales 6 from L.l. to D. ; a band along the flank ; transverse bands none . . proximus. transverse bands four . . . varius. series of scales 7 from L.l. to D. ; a band alon<^ the flank . . . orinocensis. ON THE SPECIES OF THE GENUS ANOSTOMUS. 17 3 . mouth directed forward, lower jaw little if any longer ; lower teeth short, broad, crenulate (Schizodon). series of scales 4 from L.l. to D. ; transversely banded with brown ; bands 3, a caudal band . . viltalus. bands 4, a caudal spot . fasdatus. bands blotch-like, no caudal spot dissimilis. series of scales 6 from L.l. to D. ; transverse bands absent ; rows of scales 5 between L.l. and V. isognathus. rows of scales 4 between L.l. and V. platm. mouth directed obliquely downward and forward, lower jaw shorter ; series of scales 5 from L.l. to D. . nasutus. (Anostomus.) Anostomus salmoneus Gron. Without a specimen of this species at hand it is not pos- sible to give the characters of the teeth, these having been unnoticed by previous writers. If they agree with those of the following species, as may be expected, the crenula- tion will be added to the distinouishimj; characteristics in the diao^nosis of the subgenus. Anostomus trimaculatus Kn. ; Gth. Mouth directed upward ; snout elongate, nearly round in transverse section in front of the eyes, about twice the length of the eye ; teeth crenulate in both jaws. The formula as taken from a specimen from Gurupa is D. 12 ESSEX INST. BULLETIN, VOL. XXII 2 18 ON THE SPECIES OF THE GENUS ANOSTOMUS. (13), A. 11, L.l. 45, L. tr. J^. Between the lateral line and the lirst ray of the dorsal there are six series, and between the line and tliatof the ventral but five entire series, or seven between the line and the median row of the belly. The depth of the body is three and three-fourths, and the length of the head four and one-fourth times in the total length, excluding the caudal. In the length of the head the diameter of the eye is contained four and one-half times. The fifth, or the sixth, ray of the dorsal is over the middle of the length of the body. A spot is present on the flank below the dorsal, another is seen at the base of the caudal, and there are faint indications of narrow trans- verse bands on the back, from the occiput to the end of the dorsal fin. Opercle unspotted. ( 8chizodontopsis, ) Anostomus t^niatus Kn. ; Gth. In all the species of this group the mouth opens obliquely upward and forward, the snout is broad in front of the eyes, and the teeth of the lower jaws are truncate or nearly entire on their cutting edges. On this species there are five series of scales between the lateral line and the dorsal, and four from the line to the ventral or five to tlie median series of the belly. One specimen, from Lake Hyanuary, has but four series between the line and the ventrals ; in other respects it is normal and agrees with its fellows of the same locality. There are eight rays of the dorsal in front of the middle of the body. Depth of body and length of head are equal and each is contained four and three- fourths times in the length of the body. Numerous examples from Cudajas, Iga, Jutahy, Lago Alexo, Lake Hyanuary, and Lake Saraca. ON THE SPECIES OF THE GENUS ANOSTOMUS. 19 Anostomus proximus sp. n. D. 12-13 ; A. 10-11 ; V. 9 ; L.l. 45 ; L. tr. _^. 5((i) Rather more stout than the preceding, but similar in general outline and markings. Mouth opening obliquely upward and forward, lower jaw longer, lower teeth trun- cate, upper crenulate. Snout about one and one-fifth times as long as the eye. Length of head and depth of body nearly eqnal, about two-ninths of the total length, without the caudal. The eighth ray of the dorsal is close upon the middle of the length. The row of scales from the first ray of the ventral toward the dorsal strikes the hindmost ray of the latter. Brownish, rather dark, with a band of darker from snout to tail below the lateral line. Closely allied to A. loeniatus from which it may be dis- tinguished by the smaller, more numerous scales. Hab. Villa Bella and Uerauduba. Anostomus varius sp. n. D. 12-13; A. 11-12; L.l. 45-48; L. tr. _?_. 5-(i) Depth of body, or length of head, contained four and one-third times in the length, without caudal. Much stouter than A. tamiaius of the same length. Mouth open- ing obliquely upward and forward, eight teeth in each jaw, upper crenulate, lower truncate. Back brownish, centers of scales lighter and silvery, belly silvery. A brownish band from snout to tail, below the lateral line, endinsf in a black spot. The band is rather indistinct, and of- ten obsolete. On the flank there is a transverse band of brownish behind the base of the pectoral, a second from base of dorsal to that of ventral, a third behind the dorsal, and a fourth in front of the soft dorsal. The color is us- 20 ON THE SPECIES OF THE GENUS ANOSTOMUS. uall}' darker at the points of intersection of the longitud- inal and the transverse bands. The latter are frequently indistinct, even on very youngspecimens. On large ones the depth is less than four and the head rather more than four and a half times in the total length, and the markings are greatly faded ; some have the longitudinal bands more distinct, others the transverse, and on a few all of the bands, including the caudal spot, are obsolete. Eight or nine of the dorsal rays are in front of the middle of the length. The peculiar coloration, squaniation, and stouter form serve to distinguish this fish from either of the two preceding species of this subgenus. Hob. Gurnpa, Jose Fernandez, Lake Hyanuary, Manaos, Obydos, Porto do Moz, Rio Negro. Anostomus nitens. A. varius, var. n. This name is given to a dozen light colored specimens from Iga. The transverse bands of the flank are reduced to blotches on the lateral line, the longitudinal line is faint or absent, and the general appearance is greyish rather than brown. The back is crossed by numerous narrow streaks, twenty-eight on one specimen, separated by lighter spaces of equal width. The lateral series of blotches is present on eight of the lot, while on the other four they are obso- lete, excepting the caudal spot which is much faded. The eye is large, equal to three-elevenths of the length of the head, or to the length of the snout. Niue rays of the dorsal appear in front of the middle of the length. Anostomus orinocensis St. In the desci'iption of this fish it is said there arc seven scales between the lateral line and the dorsal, and three and a half between the line and the ventral ; the latter ON THE SPECIES OF THE GENUS ANOSTOMUS. 21 statement is probably a mistake, since in the fignre given there are six. The species is nearer to proximus and va- rius than to toeniatus. (Schizodon.) Anostomus vittatus C.V. ; Gth. D. 12 ; A. 11 ; L.l. 44 ; L. tr. _i-. 4(5) This species is closely allied to A., fasciatas. It is a trifle less slender. The general appearance is darker ; of the bands across the flank the three anterior occnpy the same positions, bnt the fonrth has given place to a longi- tudinal band extending back to include the caudal spot. The snout is one and a half times the diameter of the eye. In the length of the body, without the caudal, the depth is contained three and four-fifths times, or the length of the head four and two-thirds times. The middle of the length is below the ninth dorsal ray. The mouth opens forward. The jaws are equal, and the teeth are crenu- late in both. Hah. Porto do Moz ; Goyaz. Anostomus fasciatus Sp. and Ag. ; Gth. This species is very close to the preceding. Aside from being more slender, the main dependence in distinguishing it is to be placed on the coloration, as the formula is about the same fur each. The tenth ray of the dorsal is nearly over the middle of the length, in which the depth is con- tained four and one-third and the length of the head four and two-thirds times. The mouth opens forward, the jaws are nearly equal, and the teeth are crenulate in upper and lower. The snout is about one and one-fourth times the diameter of the eye. Collected at Coary, Dutch Gui- ana, Hyavary, Iga, Jose Fernandez, Jutahy, Lago Alexo, 22 ON THE SPECIES OF TFIE GENUS ANOSTOMUS. Lake Hyanuaiy, Lake Saraca, Manacapouru, Manaos, Obydos, Eio Puty, San Paolo, Serpa, Tabatinga, Teffe, Toiiantiiis, Villa Bella. Anostomus dissimilis, sp. n. D. 12 ; A. 11 ; V. 9 ; L.l. 43-45 ; L. tr. JL. 4(5) Nearly related to both of the preceding. Darker in color than A. fasciaius, and distinguished from it, as from A. viUatus, by the absence of a spot on the base of the tail. The blotches on the flanks vary greatly, being re- duced, irregular, faint, or entirely absent. Length of head equal to the depth of body and contained in total length, without caudal, four and two-thirds times. The mouth opens forward, the lower jaw is very little the longer, the teeth are all crenulated. Twelve specimens from the Rio Puty. Anostomus isognathus Kn. ; Gth. A. Knerii St. The lateral band, figured by Kner, appears to be quite variable. Specimens from the Velhas show it still further reduced than in the form figured as A. Knerii, it being simply a black spot at the base of the caudal with faint indications of continuation forward and backward. There are five entire series between the lateral line and the ven- tral, or seven between the line and the median ventral se- ries. Mouth directed forward, jaws nearly equal, teeth crenulate in the upper and lower. Snout about one and one-half times as long as the eye. Depth three and two- thirds and leno-th of head four and one-fourth times in the total length, without caudal. The row of scales from the first ray of the ventral toward the hinder part of the dor- sal passes entirely behind the latter. ON THE SPECIES OF THE GENUS ANOSTOMUS. 23 AnOSTOMUS PLATiE, Sp. 11. D. 12 ; A. 11 ; V. 9 ; L.l. 45 ; L. tr. _L. 4(5) Mouth opening forward, lower jaw a little longer, teeth crenulute in both jaws. Length of snout equal to that of the eye. Depth of body three and one-half, or length of head four and two-thirds tin)es in the total length, with- out the caudal. The ninth ray of the dorsal fin is over the middle of the leno;th. The row of scales from the first ray of the ventral toward the hinder part of the dor- sal leads to the third ray from the end of the latter. There are six rows of scales between the lateral line and the dorsal and four between the line and the first ray of the ventral or five from the line to the median ventral se- ries. This species is stouter in front of the dorsal and more decurved about the occiput than A. isognathus; it has larger scales and a smaller number of rows on the ven- tral region. Color silvery, back darker, with lighter streak on the middle of each scale ; a faint spot at base of caudal. Hab. Rosario, La Plata. Anostomus nasutus Kn. ; Gth. Mouth opening obliquely downward and forward, lower jaw sh